Catching
Grasshoppers the Old-Fashioned Way

With all the high-tech tools
scientists have at their fingertips, sometimes the simplest device is still the
best--especially when youre counting grasshoppers.

A pane of glass and soapy water are all entomologist Dennis Fielding needs
to catch grasshoppers. He snags these pests to estimate how many are invading
cropland from surrounding areas that dont have crops. Standard sampling
methods, developed on grasslands with relatively sparse vegetation, are based
on visual counts. Fielding, an Agricultural
Research Service scientist in Fairbanks, Alaska, wants to develop a way to
conduct his grasshopper census in areas where there is a dense
canopy of cultivated crops--especially, small grains.

Grasshoppers have eaten agricultural crops--and lots of other plants--over
the course of history. They especially enjoy small grains and vegetables, which
is bad news for farmers incomes.

Fieldings traps are based on similar devices that have been catching
other insects for perhaps a hundred years. The grasshopper flies into the
vertical pane of glass and falls into soapy water. The insect then sinks
because the soap breaks the surface tension of the water. Grasshoppers may be
attracted to the trap because of the smell of their dead friends";
they are known to eat dead grasshoppers.

The traps will probably be restricted to research applications because of
their considerable cost in materials and labor and the large number needed to
get good counts. Fielding had nearly 100 traps deployed on more than two areas.
Each field had traps placed near the roadside and also in the area where crops
were growing.

Fieldings research has been under way for two years, and he thinks it
may take another two to calibrate and test the traps under a variety of
conditions.